Catheters are tube-like members inserted into the body for diagnostic or therapeutic reasons. One of the therapeutic procedures applicable to the present invention is known as percutaneous transluminal coronary angioplasty (PTCA). This procedure can be used, for example, to reduce arterial build-up of cholesterol fats or atherosclerotic plaque.
An over-the-wire catheter is characterized by a free central lumen through which a movable guidewire can be passed. Once the stenosis is located with the guidewire, a dilatation balloon catheter is advanced over a 150 cm guidewire to the stenosis location. Using such a movable wire system, one could more readily select the desired coronary artery and reach smaller branches as movable guidewires are smaller and more flexible than the fixed wire systems. Over-the-wire systems are disadvantageous because 150 cm of guidewire must be maintained outside the body either by an extension wire or by a 300 cm long guidewire. This length of guidewire is difficult to handle because it requires two operators who must be in communication during the procedure. This requires more time and risks contamination by dropping the guidewire from the sterile field. Furthermore, extension wires require additional time to assemble and their connecting parts may prevent smooth exchanges. Over-the wire systems are disadvantageous if a catheter must be exchanged for one of a different size because during the process of removing the first catheter, the guidewire may become dislodged from the stenosis resulting in the need to relocate the stenosis upon insertion of the subsequent catheter.
To respond to the disadvantage of inadvertently moving the guidewire during the exchange procedure, several methods of trapping the guidewire and holding it stationary during the exchange have been developed. One method involves a balloon built into the distal end of the catheter wall which fills the lumen around the guidewire thereby holding it stationary. A second method consists of an inflatable balloon disposed on a guidewire. Yet another method involves an accessory device which tracks the guidewire beyond the stenosis where it is deployed about the guidewire thereby holding the guidewire stationary during the exchange. Applicant's invention represents the tracking type of device.
U.S. Pat. No. 5,046,497 to Millar for "Structure for Coupling a Guide Wire and Catheter" discloses a device having a coupling structure comprising a pair of spaced-apart fingers adapted for receiving a guidewire. A guidewire is inserted through the guiding catheter. Multiple devices may be coupled to the guidewire and tracked down the guidewire and positioned in the region of interest.
U.S Pat. No. 5,131,407 to Ischinger et al for "Guide Wire with Tracking Member and Catheter Exchange System" discloses a guidewire with a helical coil surrounding the smaller diameter spring coil on the guidewire at the distal end for tracking a catheter. With the guidewire positioned in the stenosis, the catheter can be exchanged. The helically coiled tracking member can be withdrawn into the guidewire by pulling on the proximal end of the pull wire. After the guidewire has been advanced and its distal end positioned in the stenosis, and after the previous catheter has been withdrawn, a guidewire extension is attached to the proximal end of the guidewire in order that some portion of the guidewire will be exposed as the succeeding catheter is advanced over the guidewire.
U.S Pat. No. 5,167,239 to Cohen et al for an "Anchorable Guide Wire" discloses a guidewire with an inflatable balloon disposed on the distal end to anchor the guidewire in a fixed position while catheters, scopes or other instruments are advanced/retracted over the proximal end and/or body of the guidewire.
European Patent Application Publication No. 415,332 A1 and Canadian Patent Application No. A1 2,024,060 to Keith et al for "Method and Apparatus for Catheter Exchange by Guide Wire Captivation" discloses a means for selectively engaging the guidewire within the guide catheter to restrict longitudinal movement of the guidewire relative to the guide catheter. One embodiment comprises a guidewire captivation catheter and a dilatation catheter which are inserted into a guide catheter. The captivation catheter's uninflated balloon is positioned distally of the dilatation catheter's balloon. Inflating the captivation catheter's balloon pushes the dilatation catheter's guidewire against an inner wall of the guide catheter thus holding it stationary. Once inflated, however, the guide catheter lumen is obstructed thus precluding blood pressure monitoring. The physician is also precluded from injecting contrast through the guide catheter and looses the ability to move or manipulate the guidewire during the exchange. When the captivation catheter's balloon is withdrawn, a static column of blood can be created and introduce air. In the second embodiment, an inflation lumen is formed in the wall of the guide catheter between an inner wall surface and an outer wall surface at the distal end of the guide catheter. Such a design reduces the size on the guide catheter inflation lumen. Once inflated the guidewire is immobilized. The guide catheter lumen, however, is obstructed thus precluding blood pressure monitoring. In the second embodiment, the exchange balloon is a standard feature which the user pays for whether it is used or not.
European Patent Application Publication No. 416,734 A1 and Canadian Patent Application No. A1 2,022,861 to Coehlo for "Guide Catheter and Guide Wires for Effecting Rapid Catheter Exchange" discloses a guide catheter and a guidewire, one of which carries a mechanism for gripping the other during exchange of catheters over the guidewire. In one embodiment, the mechanism is an inflatable balloon on the distal end of the guide catheter. When inflated, the balloon frictionally grips the guidewire to immobilize it. In another embodiment, the mechanism is an inflatable balloon disposed on a guidewire. Once inflated, the guide catheter lumen is obstructed thus precluding blood pressure monitoring in either embodiment. The physician is also precluded from injecting contrast through the guide catheter and loses the ability to move or manipulate the guidewire during the exchange. When the captivation guidewire's balloon is withdrawn, a static column of blood can be created and introduce air. In either embodiment, the exchange balloon is a standard feature which the user pays for whether it is used or not.
What is needed is a device that facilitates the exchange of catheters without requiring the inner wall of the guide catheter to secure the guidewire, so that fluids can pass through the guide catheter while the device is securing the guidewire. The physician should also be able to move the guidewire during the exchange if desired. The device should allow any over-the-wire catheter as for example, a dilatation balloon catheter to be exchanged over any standard length guidewire without extending the guidewire or occluding the lumen of the guide catheter.